added HOSTNAME env variable

README.md

 * `server`: Your own HTTP (like the one created by http.createHttpServer).
 * `port`: The port to listen on. Defaults to the PORT environment variable, or
   8080.
-* `host`: The host to listen on. Defaults to "127.0.0.1". For the server to be
-  accessible to the outside world, listen on "0.0.0.0".
+* `host`: The host to listen on. Defaults to the HOSTNAME environment variable,
+  or "127.0.0.1". For the server to be accessible to the outside world, listen
+  on "0.0.0.0".
 * `client_utils`: Whether to add some utility functions to /webframe.js.
   Defaults to false.
 * `res404`: The string to return for a 404 error. "{{pathname}}" will be

index.js

 		} else {
 			this.server = http.createServer();
 
-			var port = options.port || process.env.PORT | 8080;
-			var host = options.host || "127.0.0.1";
+			var port = options.port || process.env.PORT || 8080;
+			var host = options.host || process.env.HOSTNAME || "127.0.0.1";
 
 			this.server.listen(port, host);
 			this.info("Listening on "+host+":"+port);